repair executable-relative boot file search on NetBSD #392

Job	Run time
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	29m 46s
ci (a6osx, macos-13)	15m 38s
ci (ta6osx, macos-13)	22m 1s
ci (arm64osx, macos-14)	8m 19s
ci (tarm64osx, macos-14)	11m 26s
ci (i3le, ubuntu-22.04)	12m 48s
ci (ti3le, ubuntu-22.04)	15m 47s
ci (a6le, ubuntu-22.04)	9m 11s
ci (ta6le, ubuntu-22.04, CFLAGS+=-std=gnu89)	11m 59s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	8m 24s
ci (i3nt, windows-2022, vs)	11m 42s
ci (ti3nt, windows-2022, vs)	14m 52s
ci (a6nt, windows-2022, vs)	11m 37s
ci (ta6nt, windows-2022, vs)	14m 40s
ci (ta6nt, windows-2022, gcc, CFLAGS+=-std=gnu89)	12m 47s
ci (ta6le, ubuntu-22.04, test-more, more)	57m 4s
	4h 28m 1s

Provide feedback